On Fri, Jun 26, 2015 at 12:27 PM, gordon chung <g...@live.ca> wrote: > > > On 26/06/2015 1:42 PM, Jay Pipes wrote: > >> On 06/26/2015 11:00 AM, gordon chung wrote: >> >>> hi, >>> >>> recently we added a change in Ceilometer to lower the size of our id >>> fields in our storage model[1]. the reason we did this was because the >>> original size of varchar(255) we assigned to ids were so large that if >>> we wanted to generate some of our larger constraint requirements, it >>> would hit index limits of the sql backend. >>> >>> [disclaimer: i'm not an expert on uuid] typically, a uuid is 36 chars >>> long, according to google, somtimes a bit longer. in Ceilometer, we >>> lowered our size to varchar(128) to get some buffer space, this >>> apparently was too restrictive on the ids we use in OpenStack as our >>> change started breaking things[2]. >>> >> >> Yeah, but come on, is >> >> "arn:openstack:heat::22990abeee3941d8aec34c09bf78d009:stacks/AutoScalingSignalTest-1278811483-JobServerGroup-g3ohap5jraxp-ghgun47tpqcs-6gd2g27t75xy/ead09b07-4fac-45b0-ad9c-489f997925fe" >> >> >> really a valid resource ID? :( >> >> so for discussion, i'm hoping to get some conditions (standardisation?) >>> on how we generate ids. most people seem to be using uuid4() to generate >>> ids -- this seems to be logical. i think the problem seems to be when we >>> add namespacing prefix. can we set a cap on namespace prefix? say >>> 32char? possibly [<optional 32char prefix>:]uuid4()? >>> >>> just brainstorming, but my main goal would be to have ids a reasonable >>> size (and hopefully consistent). >>> >> >> My suggestion would be to have a pre-processing step that would >> understand that the above monstrosity of a resource identifier can be cut >> into pieces and grab the actual UUID identifier from it in a sane way and >> put that into a VARCHAR(40) field. >> > > this is possible, but ideally Ceilometer's processing steps are more to > derive additional values rather than modify the values given to it[1]. it > also becomes a bit more daunting because Heat might not be the only service > generating ids of that length. Currently in Nova and i believe Neutron, the > id fields are also set at VARCHAR(255). as Ceilometer is (mostly) a > consumer of data, i don't think we can viably lower our id fields until the > producers enforce limitations to their own id fields. > > Keystone also generates IDs that are in excess of UUID lengths (some are sha256() hashes, some are partial DNs from LDAP, which have a maximum length of 255 iirc).
-- Morgan
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